The present invention relates to ink jet printing systems and, in particular, discloses a thermally actuated slotted chamber wall ink jet printer.
Many different types of printing have been invented, a large number of which are presently in use. The known forms of print have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.
In recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nobles has become increasingly popular primarily due to its inexpensive and versatile nature.
Many different techniques on ink jet printing have been invented. For a survey of the field, reference is made to an article by J Moore, xe2x80x9cNon-lmpact Printing: Introduction and Historical Perspectivexe2x80x9d, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).
Ink Jet printers themselves come in many different types. The utilisation of a continuous stream of ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electro-static ink jet printing.
U.S. Pat. No. 3,596,275 by Sweet also discloses a process of continuous ink jet printing including the step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still utilized by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al)
Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, by Stemme in U.S. Pat. No. 3,747,120 (1972) which discloses a bend mode of piezoelectric operation, by Howkins in U.S. Pat. No. 4,459,601 which discloses a Piezoelectric push mode actuation of the ink jet stream and by Fischbeck in U.S. Pat. No. 4,584,590 which discloses a sheer mode type of piezoelectric transducer element.
Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and by Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned referenced ink jet printing techniques rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture in communication with the confined space onto a relevant print media. Printing devices utilizing the electrothermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.
As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction, operation, durability and consumables.
There is disclosed herein an ink jet nozzle assembly including a nozzle chamber having a nozzle, the chamber including a movable portion configured for movement to effect ejection of ink from the chamber via said nozzle, and a pair of actuating arms attached to or formed integrally with the movable portion, the arms effecting movement of said movable portion as a result of one of said arms being periodically hotter than the other said arm in use.
There are many ways in which one of the arms can be made hotter than the other in use. For example, the hotter arm could have less heat sinking than the other arm. The cold arm could be in cooling water, whereas the hot arm might not be in the water. The hotter arm might have lower mass than the colder arm. A greater current might be passed through one arm making it hotter than the other. The arm to be made hotter might have greater resistance than the other arm. More electrical power might be applied to one arm, thus making it hotter than the other, or the arm to be made hotter might have more thermal insulation applied to it.
There is further disclosed herein an ink jet nozzle assembly including: a nozzle chamber having an inlet in fluid communication with an ink reservoir and a nozzle through which ink from the chamber can be ejected;
the chamber including a fixed portion and a movable portion configured for relative movement in an ejection phase and alternate relative movement in a refill phase;
a pair of spaced apart actuating arms connected with the movable portion and undergoing differential thermal expansion upon heating to effect periodically said relative movement; and
the inlet being positioned and dimensioned relative to the nozzle such that ink is ejected preferentially from the chamber through the nozzle in droplet form during the ejection phase, and ink is alternately drawn preferentially into the chamber from the reservoir through the inlet during the refill phase.
Preferably the movable portion includes the nozzle and the fixed portion is mounted on a substrate.
Preferably the fixed portion includes the nozzle mounted on a substrate and the movable portion includes an ejection paddle.
Preferably the arms extend between the paddle and the substrate.
Preferably the arms are located substantially within the chamber.
Alternately the arms are located substantially outside the chamber.
Preferably the fixed portion includes a slot a sidewall of the chamber through which the arms are connected to the paddle.
Preferably the arms are of substantially the same cross-sectional profile relative to one another.
Alternatively the arms are of differing cross-sectional profile relative to one another.
Preferably the arms are heated simultaneously.
Preferably one arm is heated to a higher temperature than the other arm.
Preferably the arms are of substantially the same material composition relative to one another.
Alternatively the arms are of substantially different material composition relative to one another.
Preferably the aims are substantially parallel to one another.
Alternatively the aims are substantially non-parallel to one another.
Preferably the assembly is manufactured using micro-electro-mechanical systems (MEMS) techniques.
Preferably an effective volume of the chamber is reduced in said ejection phase and enlarged in said refill phase.